A laboratory model for interstellar chemical evolution.

The chemistry in a supersonic plasma source flow was studied as a laboratory model for interstellar chemical evolution. It is important to match the similarity parameters for cosmic and laboratory conditions, which connect the temporal and spatial scales of the two cases. The apparatus simulated the conditions in a molecular cloud with respect to molecular-ionic reaction fraction, temperature, and non-equilibrium kinetics. The plasma flow was found to be cold enough, by the radical expansion, to produce polyatomic molecules. From the simple atomic plasma as reactant, cyanopolyyne and unsaturated hydrocarbons were synthesized in the present experiment. These molecules are also inherent in molecular clouds. The reaction mechanism is discussed.     

Corotating interplanetary streams and associated ionospheric disturbances at Venus and Earth

During the summer of 1979, solar coronal structure was such that a sequence of recurrent regions produced a corresponding sequence of corotating solar wind streams, with pronounced downstream signatures. One of these stream events passed Earth on July 3, and was observed later at Venus late on July 11th, with similar characteristics. Corresponding in-situ measurements at Earth from the Atmospheric Explorer-E satellite and at Venus from the Pioneer Venus Orbiter are examined for evidence of comparable perturbations of the planetary ionospheres. The passage of the stream shock front is found to be associated with pronounced fluctuations in n(0⁺) which appear as pronounced local depletion of ion concentrations in both ionospheres. The ionosphere disturbances appear to be closely associated with large variations in the solar wind momentum flux. The implied local ionospheric depletions observed at each planet are interpreted to be the consequence of plasma redistribution, rather than actual depletions of plasma.     

North-south asymmetries of the solar magnetic field in conjunction with the location of the heliospheric current sheet on both sides of the solar equator

Reported heliospheric current-sheet displacements from the equatorial plane have been found to be in agreement with north-south asymmetries of the solar magnetic field. Mean heliospheric sector width estimations in the period 1947–1977 have shown that the heliospheric current sheet demonstrates an asymmetric placement with respect to the solar equator. This asymmetry is very prominent in the epochs of the solar cycle minima while it almost disappears in the epochs of maxima. At the same time, the sums of the maxima values of the sunspot magnetic field intensity showed in the epochs of minimum a characteristic asymmetry which implies an essential conjunction among the heliospheric current sheet, the solar cycle and the solar magnetic field. The main conclusion which could be derived of these observations is that the heliospheric current sheet has its origin on the solar surface while its location with respect to the solar equator appears to be affected by the variability of the lower layers of the solar interior.     

Training opportunities in remote sensing in India

The paper deals with the Indian experience in training the resources scientists in the fast developing field of remote sensing and the facilities available for obtaining such training in India. The necessity of imparting training to the scientists at different levels is brought out. An outline of the training curriculum of a leading institution is described in some detail.     

Model calculations of the dayside ionosphere of Venus

Model calculations of the dayside ionosphere of Venus are presented. The coupled continuity and momentum equations were solved for O₂⁺, O⁺, CO₂⁺, C⁺, N⁺, He⁺, and H⁺ density distributions, which are compared with measurements from the Pioneer Venus ion mass spectrometer. The agreement between the model results and the measurements is good for some species, such as O⁺, and rather poor for others, such as N⁺, indicating that our understanding of the dayside ion composition of Venus is incomplete. The coupled heat conduction equations for ions and electrons were solved and the calculated temperatures compared with Pioneer Venus measurements. It is shown that fluctuations in the magnetic field have a significant effect on the energy balance of the ionosphere.     

Sunspot motions and magnetic shears as precusors of flares

Using full-disc white light photoheliograms, we have studied umbrae motion and variations in sunspot areas in a large activity complex over 4 solar rotations. On the basis of the observational data we illustrate with typical examples to what extent rapid spot motions are associated with flare occurrences.     

Simultaneous measurements of sea surface temperature by GMS-1 and GMS-2

For accurate measurements of sea surface temperature in the 11 μm window region, it is necessary to eliminate the effect of atmospheric absorption. A technique using observations from different angles is one of the methods of eliminating this atmospheric effect. This technique is not possible at present, using a single satellite; but using two geosynchronous satellites, it is possible to observe a common area from two different elevation angles. To correct for atmospheric effects, therefore, we compared the infrared data obtained from observations at about the same time (less than a minute apart) on the equator using the GMS-1 and GMS-2 satellites which had about 20° longitudinal separation. It was found that if the infrared spectral wavelength channel of one geosynchronous satellite is selected to be different from that of the other, it is possible to improve the two-satellite observation technique of estimating water vapor content in a tropical atmosphere. This technique corresponds to split window measurements by the AVHRR radiometer on board the NOAA-7 satellite.     

An instrument for DC electric field and AC electric and magnetic field measurements aboard ‘Intercosmos-Bulgaria-1300’ satellite

The instrument IESP-IPMP represents the complex unit measuring the vector of the DC electric field, the vectors of the electric and magnetic field in the frequency range of 0.2 – 6.5 Hz (wave form), autocorrelation functions of waves with frequencies of 0.1 – 5 kHz, and wave amplitudes in 8 bandpass channels. Some results are shown and compared in the various frequency ranges.     

NASA' s life sciences and space radiation biology.

Plans for the various missions in which men and women are expected to participate during the next 10 years are outlined. Such missions include flights of up to three months duration in low earth orbit as well as possible short excursions to geosynchronous orbit. Research activities are described which cover the full spectrum of physiological and psychological responses to space flight. These activities are shown to contribute to the ongoing Shuttle program and the future Space Station. The paper includes a summary of the major technical thrusts needed to support extended habitation in space.